bool is_regular_file(file_status s) noexcept;
Returns: s.type() == file_type::regular.
bool is_regular_file(const path& p);
Returns: is_regular_file(status(p)).
Throws: filesystem_error if status(p) would throw filesystem_error.
bool is_regular_file(const path& p, error_code& ec) noexcept;
Effects: Sets ec as if by status(p, ec). [ Note: file_type::none, file_type::not_found and file_type::unknown cases set ec to error values. To distinguish between cases, call the status function directly. — end note ]
Returns: is_regular_file(status(p, ec)). Returns false if an error occurs.